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    2 / 28 / 12
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    Path: BinaryBedlam > Krill Labs > procedures > How-To > Using the BT Board v1.02 JY-MCU    

Using the BT Board v1.02 JY-MCU

In Use

Cheap Bluetooth Serial Module from eBay

      This little chip is a bluetooth serial port with seemless integration into embedded devices as if you were using a standard rs232 null modem cable. They are great for short distance wireless projects that require serial console access because you can get these things on eBay for under 10 bucks. The only hard part is figuring out how they work.

      I've toyed around with one and I think I figured out the basics of wiring it up. In short, the whole device is inverted, so to connect it to an MCU/PIC directly, you would first have to set your serial parameters in the code to an inverted comms mode to compensate. If for some reason you wanted to connect this chip to a computers hardwired db9 serial port then you'd have no choice but to use a ttl converter chip like the MAX232.

      By default it transmits and receives at 9600/8/N/1. No configuration needed; right out of the box, just power it up. You can bluetooth tether to this thing with a PC using a bluetooth suite, or with your Android device! To link it to your android, first power up the chip, discover bluetooth devices, pair to "Linvor", then enter "1234". To console to it, use an app like SENA BTerm, but dont forget to first tell the app to connect to it from the list of available BlueTooth devices. When powered up, the chip will Blink Red. Even after tethering it will continue to blink. As soon as something initializes the connection by trying to send/get data, the light will switch to solid red.


Here is a single ASCII character directly out of the module.

Here is the same char after piping it through the max232.

Product Description:
Industrial serial port bluetooth, Drop-in replacement for wired serial connections, transparent usage. You can use it
simply for a serial port replacement to establish connection between MCU and GPS, PC to your embedded project and etc.
Computer and peripheral devices
GPS receiver
Industrial control
MCU projects
Default serail port setting : 9600 1
Pairing code : 1234
Running in slave role: Pair with BT dongle and master module

Coupled Mode: Two modules will establish communication automatically when powered.
PC hosted mode: Pair the module with bluetooth dongle directly as virtual serial.

Bluetooth protocal : Bluetooth Specification v2.0+EDR
Frequency : 2.4GHz ISM band
Modulation : GFSK(Gaussian Frequency Shift Keying)
Emission power : <=4dBm, Class 2
Sensitivity : <=-84dBm at 0.1% BER
Speed : Asynchronous: 2.1Mbps(Max) / 160 kbps, Synchronous: 1Mbps/1Mbps
Security : Authentication and encryption
Profiles : Bluetooth serial port

CSR chip : Bluetooth v2.0
Wave band : 2.4GHz-2.8GHz, ISM Band
Protocol : Bluetooth V2.0
Power Class : (+6dbm)
Reception sensitivity: -85dBm
Voltage : 3.3 (2.7V-4.2V)
Current : Paring - 35mA, Connected - 8mA
Temperature : -40~ +105 Degrees Celsius
User defined Baud rate : 4800, 9600, 19200, 38400, 57600, 115200, 230400,460800,921600 ,1382400.
Dimension : 26.9mm*13mm*2.2mm

Pin definition :
* PIO8 connects with LED cathodea with 470ohm series resistor in between. LED NEGATIVE connects to ground. It is used
to indicate the module state. After powered on, flashing intervals differ in different states.
* PIO9 is used to control LED indicating paring. It will be steady on when paring is successful.
* PIO11, module state switching pin. HIGH -> response to AT command; LOW or floating -> regular work status.
* With build-in reset circuit, reset is completed automatically after powered on.
* Steps to set to MASTER:
* Set PIO11 HIGH with a 10K resistor in between.
* Power on, module comes into AT Command Response Status
* Open HyperTerminal or other serial tool, set the baud rate 38400, 8 data bits, 1 stop bit, no parity bit, no Flow

* Via serial port, send characters "AT + ROLE = 1 r n",if successful, return "OK r n", where r n is carriage return.
* Set PIO11 LOW, re-power, then in Master state, automatically search for slave module and connect.

Viewer Comments

Name: George
Time: 07:01 AM
Date: May 09, 2012
Comment:     Hello there.. Nice article. i bought 2 of these boards and they work fine , i can connect to them from my phone easily ,, I just trying to figure out how am i gonna make them to work as MASTER and SLAVE, between two pc that dont have integrated bluetooth. Can you help! thanks

Name: Juan Carlos
Time: 10:49 AM
Date: May 09, 2012
Comment:     Hi there, would you pls explain what is PIO11? I got this device yesterday, but I can`t work with it. I can get connected, but when I send data, viewing on hyperterminal, there characteres are rare, as if speed where different. By default it`s 9600/8/N/1 as you say right? I don`t how to make at commands work `cause that pin I told you. Do I have to broke plastic coverage? I hope you can help me, thank you so much.

Name: bluegoo
Time: 06:35 PM
Date: May 22, 2012
Comment:     pio11 is not connected to any of the pins on the module, Key pin is connected to PIO3? your pics do not show a kludge to connect to PIO11..missing something?

Name: bluegoo
Time: 12:37 PM
Date: May 23, 2012
Comment:     to clarify..if you serach ebay you will notice that on some of the raw modules "KEY" is connected to PIO11(34) and others to PIO3(26), some of the carrier boards have traces from both PIO11(34) and PIO3(26) to the "KEY" hdr pin, others do not, some one or the other. tracing with a ohmmeter confirms what it really is. Another possiblity is that the KEY pin on the Header has no pin! that may be a red flag! Ther are some BT carriers with the hdr actually soldered in..that may be because those actually work and the ones that do not have the hdr pin do not work as MASTER AND?OR SLAVE but only as SLAVE. Bottomline is methinks all these modules are not the same firmware(programmable IO pins are different) and the carrier boards are obviously not all the same.

Name: Cyber37
Time: 12:55 PM
Date: September 19, 2012
Comment:     Hi man, i have the module it look`s like the same as your module .. But, i power it on, the led is blinking (red led) and from my phone i see "linvor" bluetooth wireless, i can associate to it with the password, BUT i cant connect to the module .. I have try with blueterm Sena Bterm etc i cant .. And i have also a problem with AT commands, but i need to buy a RS232 link first for see what`s the problem exactly ..because i am trying from my Stm32 discovery to send data`s and it doesn`t work (for exemple for change the bluetooth name but it`s possible that the problem is my program so for it i need to buy a cable ftdi

Name: chanaka
Time: 10:00 AM
Date: September 24, 2012
Comment:     Can i use this with a 5v microcontroller. This says it is 3.3v . Has anyone tried it with 5v.

Name: JA
Time: 07:00 PM
Date: September 26, 2012
Comment:     Board says its accepts anything from 3.3v to 6v.

Name: KDM
Time: 03:35 PM
Date: October 26, 2012
Comment:     Define "inverted." My experience of using the PIC USART is that the serial comms is, by default, inverted. This (presumably) is so that when it`s connected to the MAX232, it inverts again resulting inthe signal being correct. I assume you`re talking about a software bit-bang implementation, where you clock the bits out in software. I hope I`m right and I can jsut hang this device right off the PIC USART.

Name: KDM
Time: 04:17 PM
Date: November 10, 2012
Comment:     Yep. I was right. If I coe up for teh PIC USART in RISC, the PIC connects directly. I potted down the PIC Tx line to 3.3V and it works a charm!

Name: Fildev
Time: 01:24 PM
Date: December 05, 2012
Comment:     Board will only be able to set to MASTER if it is a HC-05 version. The HC-06 version doesn`t have the AT+ROLE possibility. If you enter the AT+VERSION command and get Linvor ver1.5 back then it`s a no go for MASTER. If you get HC-05 back then it will go. PIO11 is accesible on bottom of pcb at "KEY" terminal. Best to connect to 3.3V or true voltage divider.

Name: Xlam
Time: 12:08 PM
Date: December 12, 2012
Comment:     Please tell me if this device is ONLY for Arduino?

Name: James
Time: 12:18 PM
Date: January 04, 2013
Comment:     Ant thoughts on this- I have connected it via a serial<>ttl adapter to my PC, and via Blueooth to an android tablet. Terminal emulator testing shows stuff I type on the PC appears in the Android terminal screen, but not the other way - seems to only be working in one direction?

Name: Gailen
Time: 03:00 PM
Date: January 25, 2013
Comment:     I have a V1.05 board which like the picture has no pins on the "Key" and "State" terminals. Do they connect to the BT module itself or are they blank, not connected? If they are connected, which one should put it in AT mode?

Name: Chris
Time: 09:44 PM
Date: January 26, 2013
Comment:     I have the same module. I don`t need to pull up or down the Key (nor State) pins in order to issue AT commands. However, I found I have to send the command characters to it with no more than 1/18th second between characters. Try sending AT+VERSION to it, if that doesn`t reply with the firmware version, it is too slow. Make sure it is responding to AT with OK, otherwise the baud may be incorrect. Cycle through them to recover.

Name: Gailen
Time: 08:49 AM
Date: January 27, 2013
Comment:     Thanks Chris. What serial program are you using to send the AT command?

Name: Chris
Time: 11:38 AM
Date: January 27, 2013
Comment:     I am using a Parallax Prop micro, and I used their Parallax Serial Terminal to send what I type to code I wrote, that relays the characters to the BT module, which is connected to Prop I/O pins.

Name: Gailen
Time: 01:56 PM
Date: January 27, 2013
Comment:     I don`t have or have access to the Parallax board. I`m connecting thru usb to serial port. Any suggestions as to what terminal program to use? It will be used to communicate with an RC radio for programing. I`ve been told it needs to be 115k baud. That`s why I need to get into it.

Name: Chris
Time: 03:03 PM
Date: January 27, 2013
Comment:     Windows Hyperterminal has a programmable character delay on the Properties/Settings/AsciiSetup form

Name: Chris
Time: 03:09 PM
Date: January 27, 2013
Comment:     I ran across an arduino sketch documenation that backs up the per-character delay.

Name: Chris
Time: 03:09 PM
Date: January 27, 2013
Comment:     Try again

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